Disposable body fluid pressure monitor

ABSTRACT

A pressure monitoring device is disclosed which is designed to be discarded after each use. This device utilizes a tube which is separated by a flexible diaphragm. One end of the tube is attached to the source of pressure, and the distal end is attached to a pressure sensing device. The pressure sensing device is of any standard reusable type and it does not require sterilization. The tube and its components are made of inexpensive, sterilizable material and are designed to be disposed of after one use.

United States Patent 1 Ramsey, III

[ DISPOSABLE BODY FLUID PRESSURE MONITOR [75] Inventor; Maynard Ramsey,III,

[73] Assignee: Ramtech, Inc., Tampa, Fla.

[22] Filed: Oct. 28, 1970 [21] Appl. No.2 84,718

Related U.S. Application Data Durham,

[63] Continuation-impart of Ser. No, 881,121, Dec. 1

1969, Pat. No. 3,648,687.

[52] US. Cl. ..l28/2.05 D, 73/409 [51] Int. Cl. ..A61b 5/02 [58] Fieldof Search ..l28/2.05 D, 2.05 E; 215/82,

[56] References Cited UNITED STATES PATENTS 2,535,998 12/1950 Bierman..l28/2.05 D 2,066,889 1/1937 Kay ..215/82 X 2,600,324 6/1952 Rappaport...128/2.05 D 2,648,328 8/1953 Hathaway et a1..... ...128/2.05 D3,418,853 12/1968 Curtis ..128/2.05 E

l lMalCIl 13, 1973 2,866,453 12/1958 Jewett ..l28/2.05 D

FOREIGN PATENTS OR APPLICATIONS 227,741 1/1925 Great Britain ..215/82OTHER PUBLlCATIONS Anesthesiology, Vol. 18, No. 6, Nov.-Dec., 1957, pp.

Surgery, V01. 61, 1967, May, pp. 711-712. Surgery, V01. 64, No.6, Dec.,1968, p. 1161.

Primary Examiner- Kyle L. Howell Att0rneyF1eit, Gipple & Jacobson [57]ABSTRACT 8 Claims, 5 Drawing Figures PATENTEDHAR1319T5 FIG.4

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INVENTOR. MAYNARD RAMSEYIH BY 772. m ATTORNEY.

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DISPOSABLE BODY FLUID PRESSURE MONITOR This is a continuation-in-partapplication of my copending application, Ser. No. 88l,l2l, filed Dec.ll, 1969 now U.S. Pat. No. 3,648,687.

BACKGROUND OF THE INVENTION 1. Field of the Invention This inventionrelates to pressure indicating devices of the type used for themeasurement of body fluid pressures and more particularly to a directreading, disposable hypodermic manometer adapted for use in themeasurement of arterial, venous blood and cerebrospinal fluid pressures.

2. Description of the Prior Art The pressures of fluids in the vesselsof all living things are indications of many facts which are of greatvalue to those engaged in medical, biology and related fields. In thecase of humans, the pressure in the vascular system is measured for manyreasons, including diagnosis of pathology, laboratory routine forcertain ailments, ascertainment of the progress of therapy, etc. Forinstance, the determination of venous blood pressure is an essentialelement in the diagnosis of a patient suspected of cardiac disease. Anormal venous pressure ranges between 80-120 millimeters water, whereaselevations of venous pressure above that range are found in cases ofcongestive heart failure.

Similarly, cerebrospinal fluid pressure is nonnally 70-180 millimeterswater, whereas elevated pressures may be found, for example, in cases ofintracranial tumor, supperative encephalitis, and cerebral abscess,hydatid cysts, extra, subdural, subarachnoid and intra cerebralhemorrhage, meningitis, acute encephalitis, hydrocephalus,craniostenosis, cerebral edema following head injury, acute nephritis,hypertensive encephalopathy and eclampsia. Lower than normalcerebrospinal pressures may be observed in. such cases as spinal blockby tumor, some subdural hematomas, and intracranial space occupyinglesions which produce displacement of normal structures to causepressure coning at the foramen magnum or tentorial opening.

The most common method of obtaining arterial blood pressure has been togradually apply constrictive pressure about the limb of the patientuntil the flow of blood through a vessel has been arrested, asdetermined by listening to a stethoscope applied over the vessel at apoint distal the point of constriction. Then, upon gradual release ofthe constricted pressure, the beginning of the flow through the vesselcan be heard and the constricted pressure is noted on the gauge readingin millimeters of mercury. The pressure that is noted is the diastolicpressure. The pressure is then further gradually released until thesounds of the flow again cease and the pressure is again noted; thisbeing the systolic pressure. The difference between the two pressure istermed the pulse pressure. The constriction pressure heretofore has beenderived from an inflatable cup connected to a mercury column manometeror to an aneroid type gauge having a dial scale calibrated inmillimeters of mercury. While this common device is satisfactory formeasuring the diastolic-systolic pressure range for a discreet period oftime, it has the obvious disadvantage of not being able to continuouslymonitor the patients blood pressure.

In the prior art, many attempts have been made to devise blood pressuregauges which are portable, inexpensive and yet provide the attendingphysician with an accurate determination of the patients blood pressure.One such device employs telescopically related, spring loaded tubes, thetubes being biased in an extended position. By exerting axial pressureon the tubes against an artery until blood flow in that artery is cutoff, and by monitoring the relative displacement of the tubes from thefully extended position. required to produce such flow out off, thesystolic pressure is monitored. However, the means for monitoring thedisplacement of the tubes is often inconvenient or clumsy. For example,another prior art device is cited which employs a pointer extending froman inner tube through a longitudinal slot in an outer tube, the outertube having calibrated markings adjacent the slot. The disadvantage withthis arrangement lies in the fact that the tubes, and hence the pointer,return to the original biased position upon removal of the instrumentfrom the body, thereby requiring the operator to take a reading whileexerting direct pressure. Such a technique has been found to beinconvenient.

Generally speaking, however, the indirect methods of making fluidpressure measurements, such as the ones cited above, are not as accurateas any method which utilizes the particular fluid itself operatingdirectly against a pressure sensing device.

However, the direct-measuring apparatus now in use for measurement ofarterial-venous and cerebrospinal fluid pressures of human subjects areexpensive difficult to assemble, clean and reuse. It would thus be anadvantage to develop a direct intra-vessel pressure measuring devicewhich allows for continuous monitoring of the level of pressure while atthe same time being simple, inexpensive and disposable so as toeliminate the sterilization problems.

OBJECTS OF THE INVENTION Therefore, it is an object of this invention toprovide a hypodermic pressure manometer especially adapted for themeasurement of arterial or vascular blood and cerebral fluid pressure,such device designed to be disposed after one use.

Another object of this invention is to provide a portable instrument forthe above uses which is adapted for carrying in a doctor's valise, thusproviding a useful diagnostic instrument for the general practioner.

Still another object is to provide a direct reading, self-contained,mechanical hypodermic pressure manometer which is used in conjunctionwith a standard aneroid manometer or other sensing device and which isdisposable after each use.

A further object is to provide an apparatus for the measurement of fluidpressures in humans and animals which can be used safely, quickly andeasily by laboratory technicians without any particular skill other thanthat provided by conventional training.

A still further object of the invention is to provide an apparatus ofthe character described which has no moving parts; which requires nopower source for operation; which utilizes no chemicals or additionalapparatus or instruments; and which is readily transportable.

Another object of this invention is to provide a manometer which is sosimple and inexpensive in construction that it may be discarded afteruse instead of being washed and re-sterilized, and whereby the onlysterilization required is at the place of manufacture wheresterilization and adequate testing to assure sterility can be effectedin mass production at little cost.

Other objects of the invention will in part be obvious and will in partappear hereinafter in the summary of the invention and in the detaileddiscussion of the preferred embodiments.

SUMMARY OF THE INVENTION The above objects are efficiently obtained byproviding a tube or barrel with a flexible diaphragm which seals thetube into an upper and lower plena. The lower plenum is connected to asuitable catheter and hypodermic needle. In one embodiment this lowerplenum is filled with a suitable incompressible fluid for improvedsensitivity to pressure differentials and in a second embodiment a gassuch as air may be utilized. The upper plenum is adapted to receive apressure sensing or recording instrument such as a standard ane roidmanometer. In one embodiment the upper plenum may be filled with anincompressible fluid while in another embodiment a gas such as air maybe utilized to transmit the pressure differentials to the manometer.

The device is designed to be sterilized and packaged at the point ofmanufacture and thrown away after one use. The standard pressure sensingdevice is attached at the point of use and because of the sterilizeddiaphragm, it may be used repeatedly without sterilization. In addition,this device is provided with a frangible end cover which is visiblyruptured at the time of first use thereby forestalling an accidentalreuse.

'The invention accordingly comprises the features of construction,combination of elements and arrangement of parts which will beexemplified in the construction hereinafter set forth and the scope ofthe invention will be indicated in the claims.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an exploded view of oneembodiment of the disposable manometer of the present invention.

FIG. 2 is a planar cross-sectional view of one embodiment of thedisposable manometer of the present invention.

FIG. 3 is a bottom view through line 3-3 of FIG. 2.

FIG. 4 is a partial, planar view along line 4-4 of FIG. 2. 1

FIG. 5 is a front, sectional, planar view of the disposable manometer ofthis invention.

Similar reference characters refer to similar parts throughout theseveral views of the drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to thedrawings, one device embodying the disposable manometer of the presentinvention is shown and generally referred to by the reference number 10.Manometer comprises a tube or barrel 12 having at one end a catheter orhypodermic needle connector 14 and at the distal end a tube orifice l8adapted to receive pressure sensing means such as standard aneroidmanometer 16 or other standard pressure sensing or recording device (notshown). Inserted within tube 12 is a flexible diaphragm 20 which isplaced in an airtight seal when a resilient stopper 22 or the like isfitted into tube orifice 18. Within diaphragm 20 is diaphragm openingmeans such as insert 24, the function of which is to insure thediaphragm 20 is in the open position shown in FIG. 2 when disposablemanometer 10 is being used. Insert 24 may be made of any generalized,lightweight configuration which will freely fit within diaphragm 20 or,if liquid is utilized within diaphragm 20, discussed infra, then insert24 may be eliminated from disposable manometer l0 completely.Surrounding tube orifice 18 are radially extending finger flanges 26which are integral with tube 12 and may be used to aid in the insertionand removal of the nipple 28 of a standard aneroid manometer 16 or otherpressure sensing or recording device (not shown) being used to sense thetransmitted pressures. While flanges 26 are used to help insertion andremoval of nipple 28, their primary function is to act as a stop toprevent retaining band 30 from slipping off the end of tube 12.Surrounding the outer end 32 of rubber stopper 22 are stopper retainingmeans in the form of an end cover 34 which serves the function ofinsuring that stopper 22 remains seated in an airtight relationship withtube orifice 18. End cover 34 is here shown to be generally rectangularand having holes 36 which are arranged to receive retaining band 34 asillustrated by FIG. 5. This arrangement insures that an airtight sealwill remain between stopper 22 and tube orifice 18. In addition, duringoperation of disposable manometer 10, end cover 34 insures that stopper22 will not'be forced out of its sealing relationship with tube orifice18 even if the pressure within tube 12 becomes very high.

In addition, end cover 34 has the secondary function of a frangiblemembrane which insures that disposable manometer 10 is not accidentallyused a second time. End cover 34 may be made of thin plastic or anysimilar substance which has sufficient tensile strength to allow it tobe used as the retaining means for stopper 22 while at the same timehaving a relatively low resistance against rupture to the penetrating,transverse force of nipple 28 as it is forced into hole 38 of stopper22. In the alternative, a hole of smaller diameter than stopper hole 38may be placed in end cover 34 and this hole registered over stopper hole38 to act as a starter in the insertion of nipple 28.

In operation, the various elements of the device, excluding aneroidmanometer 16, are sterilized, assembled and individually packaged at theplace of manufacture. The component parts are made of inexpensivematerial such as plastic and the like and the device is designed to bedisposed of after one use. At the point of use, the package is openedand the device removed. The manometer 10 may have a standard catheter 42and hypodermic needle (not shown) already attached at the factory orthey may be attached at the time of use. It is contemplated that thelower plenum 44 of the manometer l0 defined by the lower end of tube 12,diaphragm 20 and catheter connector 14, together with catheter 42 and ahypodermic needle (not shown), if connected, may be filled with aheparinized saline or similar solution to insure that no air is trappedin that portion of the system. Alternatively, the lower plenum 44 maycontain air which will be compressed when catheter 42 is connected to asource of super-atmospheric pressure. In addition to the above it isfurther contemplated that bleeding means such as a valve 46 be placed inthe wall of tube 12 to allow air to be bled out of the system as blood(not shown) or other fluid is drawn into catheter 42 and lower plenum44.

Upper plenum 48 may be filled with a non-corrosive, non-compressible,liquid which will aid in the transmission of undampened pressurevariations, especially if fluid is also utilized in lower plenum 44. Ifthe plena are to be filled with air, the pulsations will be dampened. Iffluid fills upper plenum 48 then there is no need for insert 24 and theembodiment of end cover 34 without hole 40 must be used in order toprevent fluid leakage prior to insertion of manometer 10. Alternatively,however, stopper hole 38 may be plugged with a removable plug (notshown) or the like to prevent leakage prior to use.

After manometer is removed from its sterilized container, the userinserts aneroid manometer 16 or other sensing recording device intostopper hole 38, thereby rupturing end cover 34. When determining venouspressure, a tourniquet is applied to the upper arm of the patient andperforming vein puncture with the hypodermic needle (not shown) in theusual fashion. When no fluid is utilized in either plena 44 and 48,entrance of the needle into the vein is confirmed by the visualindication of a flow of blood into catheter 42. The tourniquet isthereupon released, allowing an equilibration of pressure. At this timediaphragm 20 will transmit the pressure variations to the indicatingfluid in upper plenum 48 which consequently causes registration on themanometer dial 50. After the arterial or venous pressure has beenmonitored, the hypodermic needle (not shown) is removed from the veinand manometer 16 removed from stopper 22. The disposable manometer 10 isthen discarded.

When measuring cerebrospinal fluid pressure, the device is assembled inthe same way as before. Spinal puncture is performed in a well knownmanner, e.g., by lying the patient on his side with his knees flexed.The area to be pierced, usually thethird or fourth lumbar interspace, isprepared by sterile cleansing, then infiltrated with one percentprocaine and then the hypodermic needle (not shown) is inserted into thearea. Penetration into the spinal canal may be felt by the giving way ofthe spinal ligaments. If the needle is properly located, there will be avisual indication of the cerebrospinal fluid therein.

In so far as the specific dimensions of disposable manometerrltl, itiswithin the contemplation of this invention that tube 12 could be ofanother cross section such as rectangular, triangular, oval and etc.Further, it is contemplated that catheter connector 14 be locatedeccentrically with tube 12 or even transversely located on the side wallof tube 12.

It is also contemplated that diaphragm 20 could be molded into tube 12at any location along its length or, it could be attached to catheterconnector 14 or any other suitable location to isolate lower and upperplena 44 and 48.

It is also contemplated that the hypodermic needle be connected directlyto tube 12, hence dispensing with catheter 42.

The various elements of manometer 10 may be made of any suitably ridged,lightweight substance which will facilitate easy handling and use.

it will thus be seen that the objects set forth above and those madeapparent from the preceding detailed description are efficientlyattained and since certain changes may be made in the above constructionwithout departing from the scope of the invention, it is intended thatall matter contained in the above detailed description or shown in theaccompanying drawings, shall be interpreted as illustrative and not in alimiting sense.

It is also understood that the following claims are intended to coverall the generic and specific features of the invention herein described,and all statements of the scope of the invention, which as a matter oflanguage, might be said to fall therebetween.

Now that the invention has been described:

What is claimed is:

l. A disposable device for use in a fluid-pressure monitor, comprisingan elongated tubular container, means on one end of said tubularcontainer adapted to place the interior of said tubular container incommunication with the system to be monitored, a flexible imperviousdiaphragm received within said tubular structure, said diaphragmseparating said tubular container into upper and lower chambers, insertmeans placed within said upper chamber to maintain said diaphragm in anextended position, a one-hole resilient stopper mounted in said otherend of said tubular container, said stopper extending into saiddiaphragm to form a fluid tight seal between the internal surface ofsaid tubular container, said diaphragm, and the external surface of saidstopper, said stopper being adapted to receive pressure sensing meanstherein, a stopper cover engaging said stopper, said stopper cover beingbiased against the external surface of said container in a fixedrelationship by a retaining band to prevent accidental dislodging ofsaid stopper.

2. A disposable device as claimed in claim 1, including pressure-sensingmeans removably inserted into said stopper hole and sealingly' receivedtherein to record pressure variations within said upper chamber.

3. A disposable device as claimed in claim 2 wherein said pressuresensing means comprises a standard ane' roid manometer having a pressuresensing nipple.

4. A disposable device as claimed in claim 1, wherein said elongatedtubular structure has said other end terminating in a radial flangewhich acts as a stop to prevent said retaining band from slipping offthe end of said tubular container.

5. A disposable, device as claimed in claim 1,

wherein said stopper cover is seated over said stopper to cooperate withsaid stopper to seal said stopper hole.

6. A disposable device as claimed in claim 1, wherein said stopper coveris a frangible membrane.

7. A disposable device as claimed in claim 1, wherein said lower chambercontains a saline solution.

8. A disposable device for use in a fluid-pressure monitor comprising anelongated tubular container having a flanged end and a constricted flowend, means on said constricted flow end of said tubular containeradapted to place the interior of said tubular container in directcommunication with the fluid system to be monitored, a flexibleimpervious flngershaped diaphragm having a closed lower end and an openupper end received within the flanged end of said tubular containerseparating said tubular container into an upper chamber and a lowerchamber, insert means placed within said upper chamber to maintain saiddiaphragm in an extended position, bleeding means connected to the wallof said tubular container and communicating with said lower chamber, aone-hole

1. A disposable device for use in a fluid-pressure monitor, comprisingan elongated tubular container, means on one end of said tubularcontainer adapted to place the interior of said tubular container incommunication with the system to be monitored, a flexible imperviousdiaphragm received within said tubular structure, said diaphragmseparating said tubular container into upper and lower chambers, insertmeans placed within said upper chamber to maintain said diaphragm in anextended position, a one-hole resilient stopper mounted in said otherend of said tubular container, said stopper extending into saiddiaphragm to form a fluid tight seal between the internal surface ofsaid tubular container, said diaphragm, and the external surface of saidstopper, said stopper being adapted to receive pressure sensing meanstherein, a stopper cover engaging said stopper, said stopper cover beingbiased against the external surface of said container in a fixedrelationship by a retaining band to prevent accidental dislodging ofsaid stopper.
 1. A disposable device for use in a fluid-pressuremonitor, comprising an elongated tubular container, means on one end ofsaid tubular container adapted to place the interior of said tubularcontainer in communication with the system to be monitored, a flexibleimpervious diaphragm received within said tubular structure, saiddiaphragm separating said tubular container into upper and lowerchambers, insert means placed within said upper chamber to maintain saiddiaphragm in an extended position, a one-hole resilient stopper mountedin said other end of said tubular container, said stopper extending intosaid diaphragm to form a fluid tight seal between the internal surfaceof said tubular container, said diaphragm, and the external surface ofsaid stopper, said stopper being adapted to receive pressure sensingmeans therein, a stopper cover engaging said stopper, said stopper coverbeing biased against the external surface of said container in a fixedrelationship by a retaining band to prevent accidental dislodging ofsaid stopper.
 2. A disposable device as claimed in claim 1, includingpressure-sensing means removably inserted into said stopper hole andsealingly received therein to record pressure variations within saidupper chamber.
 3. A disposable device as claimed in claim 2 wherein saidpressure sensing means comprises a standard aneroid manometer having apressurE sensing nipple.
 4. A disposable device as claimed in claim 1,wherein said elongated tubular structure has said other end terminatingin a radial flange which acts as a stop to prevent said retaining bandfrom slipping off the end of said tubular container.
 5. A disposable,device as claimed in claim 1, wherein said stopper cover is seated oversaid stopper to cooperate with said stopper to seal said stopper hole.6. A disposable device as claimed in claim 1, wherein said stopper coveris a frangible membrane.
 7. A disposable device as claimed in claim 1,wherein said lower chamber contains a saline solution.